JP2902160B2 - Method for manufacturing semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor light emitting device having a D array.

[0002]

2. Description of the Related Art For example, it has been proposed to use an LED array as a light source for exposure of a photosensitive drum of a page printer.

As a substrate of such an LED array,
Silicon (Si) is suitable because of its high strength, good thermal conductivity, and low cost. As an LED, gallium arsenide (GaAs) having good light emission characteristics and high electron mobility is used.
s), a compound semiconductor such as aluminum gallium arsenide (AlGaAs) is suitable. In forming such a semiconductor on a silicon substrate, metal-organic vapor phase epitaxy (MOCVD), molecular beam epitaxy (MBE)
Thus, it is suitable from the viewpoint of mass productivity and the like that a semiconductor crystal is epitaxially grown on a silicon substrate and the epitaxial layer forms an LED array.

[0004] However, no specific method of manufacturing a semiconductor light emitting device having an LED array on a silicon substrate has been proposed.

Further, when a semiconductor crystal such as gallium arsenide is epitaxially grown on a silicon substrate, misfit dislocation due to a difference in lattice constant between the silicon crystal and the semiconductor crystal and dislocation in the silicon crystal are inherited in the semiconductor crystal. As a result, a defect occurs in the semiconductor crystal layer due to dislocations, a natural oxide film on the silicon substrate, or the like. Such defects in the semiconductor crystal layer degrade the light emitting characteristics of the LED.

Therefore, as shown in FIG. 12, a semiconductor crystal serving as a buffer layer 102 is first grown on a silicon substrate 101, and then a semiconductor crystal serving as an N-type semiconductor layer 103 and a P-type semiconductor layer 104 are grown. It has been proposed to configure an LED with the semiconductor layers 103 and 104.

FIG. 11 shows the relationship between time and temperature when the buffer layer 102 is formed. First, silicon substrate 1
01 is removed at a high temperature of about 950 ° C. Next, the temperature is once lowered and then raised to about 660 ° C. to grow a semiconductor crystal mainly constituting the buffer layer 102. In order to apply thermal stress to the semiconductor crystal layer 102a, a cycle of once lowering the temperature and then increasing the temperature to about 850 ° C. is repeated a plurality of times. Due to the thermal stress, as shown by a broken line 105 in FIG. 12, dislocations are confined in the buffer layer 102 or escaped to the side, thereby reducing dislocations in the semiconductor layers 103 and 104 constituting the LED.

Further, a single strained superlattice layer 106 is provided in the middle of the semiconductor crystal layer 102a constituting the buffer layer 102.
12, the dislocation is confined inside the buffer layer 102 or escapes to the side as shown by a broken line 107 in FIG. 12, and the semiconductor layers 103 and 104 constituting the LED are formed.
Dislocations are reduced.

[0009]

Specifically, as a method of forming an LED array on a silicon substrate, a semiconductor crystal is epitaxially grown on one entire main surface of the silicon substrate, and unnecessary portions of the epitaxial layer are removed by photolithography or the like. It is conceivable that the LED array is removed by the above method.

However, since gallium arsenide or the like, which is preferable as an LED material, has a different coefficient of thermal expansion from silicon, these semiconductor crystals are epitaxially grown on the entire main surface of one side of the silicon substrate at a high temperature inside the reactor. If the temperature is lowered, the substrate is warped, cracks occur in the epitaxial layer, and there is a problem that current leaks therefrom.

Further, the defects of the semiconductor crystal layer grown on the silicon substrate cannot be sufficiently reduced even by forming the buffer layer 102 as described above. Specifically, E.C. P. D. (etch pit dens
ity) could not be reduced to 1 × 10 ⁶ / cm ² or less.
This is because, as shown by a broken line 108 in FIG.
3, 104.

Further, as shown in FIG. 13, a strained superlattice layer 106 formed in the middle of the buffer layer 102 has a first semiconductor crystal 106a having a different lattice constant from the semiconductor crystal 102a mainly constituting the buffer layer 102, Second semiconductor crystal 106 having a different lattice constant from first semiconductor crystal 106a.
b is alternately repeated a plurality of times for growth. For example, when the semiconductor crystal 102a that mainly constitutes the buffer layer 102 is a gallium arsenide crystal, the first semiconductor crystal 106a of the strained superlattice layer 106 is an indium gallium arsenide (InGaAs) crystal, and the second semiconductor crystal 1
06b is a gallium arsenide crystal. Accordingly, in the strained superlattice layer 106, a stress acts between the growth layer of the first semiconductor crystal 106a and the growth layer of the second semiconductor crystal 106b in a direction perpendicular to the growth direction (vertical direction in FIG. 13). I do. Due to this stress, a strain is generated in the strained superlattice layer 106 in a direction perpendicular to the growth direction.
Are equally distributed along the growth direction as indicated by arrows. Due to such strain in the strained superlattice layer 106,
As described above, the dislocation 107 is confined inside the buffer layer 102 or escapes to the side.

However, since the strained superlattice layer 106 causes a strain in the epitaxial layer of the semiconductor crystal,
As shown by a broken line 109 in FIG.
The upper end side (upper side in the figure) of the growth direction 06 is a source of dislocation. Therefore, even if the strained superlattice layer 106 is formed in the middle of the buffer layer 102, the E.C. P. D. Cannot be reduced.

An object of the present invention is to provide a method for manufacturing a semiconductor light emitting device that can solve the above technical problems.

[0015]

A feature of the first invention is that a part of a silicon oxide film formed on one main surface of a silicon substrate is removed, thereby using the silicon oxide film as an insulating mask. The semiconductor crystal mainly constituting the buffer layer is epitaxially grown on the silicon substrate portion selected by the insulating mask, a strained superlattice layer is formed in the buffer layer, and the strain of the strained superlattice layer is grown. The difference is along the direction, the portion where the strain is the largest is disposed below the upper end in the crystal growth direction, and the semiconductor crystal constituting the LED is epitaxially grown on the buffer layer.

A feature of the second invention is that a part of the silicon oxide film formed on one main surface of the silicon substrate is removed, thereby insulating the silicon oxide film formed on the one main surface. A semiconductor crystal mainly constituting a buffer layer is epitaxially grown on a silicon substrate portion selected by the insulating mask as a mask, and a plurality of strained superlattice layers having different strain magnitudes are spaced apart in the crystal growth direction in the buffer layer. The strained superlattice layer having the largest strain is arranged below the uppermost strained superlattice layer in the crystal growth direction, and the semiconductor crystal constituting the LED is epitaxially grown on the buffer layer. is there.

[0017]

According to the present invention, a part of the silicon oxide (SiOx) film formed on one main surface of the silicon substrate is removed, thereby using the silicon oxide film as an insulating mask. The semiconductor crystal can be epitaxially grown by selecting only a necessary portion of one of the main surfaces. Therefore, compared with the case where a semiconductor crystal is grown on the entire surface of one main surface of the silicon substrate, the warpage of the substrate due to the difference in the thermal expansion coefficient between silicon and the semiconductor crystal is reduced,
Cracks can be prevented from entering the epitaxial layer.

According to the structure of the first aspect of the present invention, the magnitude of the strain in the strained superlattice layer formed in the buffer layer varies along the growth direction, and the portion where the strain is greatest is in the crystal growth direction. It is located below the upper end. This allows
By reducing the strain at the upper end in the growth direction of the strained superlattice layer, it is possible to reduce the occurrence of dislocations from the upper end in the growth direction, and to maximize the strain below the upper end in the growth direction. As a result, dislocations can be effectively confined in the buffer layer or can be released to the side.

According to the configuration of the second aspect of the present invention, among the plurality of strained superlattice layers formed in the buffer layer, the strained superlattice layer having the largest strain is higher than the strained superlattice layer at the top in the crystal growth direction. It is located below. Thus, by reducing the strain on the upper end side in the growth direction of the strained superlattice layer in the uppermost direction in the crystal growth direction, it is possible to reduce the occurrence of dislocations from the upper end side in the growth direction, and to reduce the strain in the crystal growth direction. By maximizing the strain of the strained superlattice layer below the upper strained superlattice layer, dislocations can be effectively confined inside the buffer layer or released to the side.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 5 and 6 show the structure of a semiconductor light emitting device 4 having an LED array manufactured by the method of the present invention, wherein a plurality of mesa-shaped LEDs 5 are provided on one main surface 1a of a silicon substrate 1. FIG. Are formed in rows.

One main surface 1a and the other main surface 1b of the silicon substrate 1 are covered with silicon oxide films 2a and 2b formed by a thermal oxidation method. The silicon oxide film 2a covering one main surface 1a is partially removed to form an insulating mask. The epitaxial layer 3 is formed on the silicon substrate portion selected by the insulating mask, that is, on one main surface 2a not covered with the silicon oxide film 2a. This epitaxial layer 3 includes a buffer layer 3a, an N-type semiconductor layer 3b, a P-type semiconductor layer 3c,
And a P-type semiconductor layer 3d containing a large amount of dopant. The LED 5 is constituted by the semiconductor layers 3b, 3c and 3d of the epitaxial layer 3. The epitaxial layer 3 is covered with a passivation film 9. The electrodes 6a and 6b are connected to the P-type semiconductor layer 3d containing a large amount of dopant and the other main surface 1b of the substrate 1. The electrode 6
a and 6b are, for example, chrome gold (CrAu).

A method of manufacturing the semiconductor light emitting device 4 will be described with reference to FIGS.

First, as shown in FIG.
Silicon oxide films 2a and 2b are formed on the entire surface of one main surface 1a and the other main surface 1b by a thermal oxidation method. More specifically, the silicon substrate 1 is oxidized in an oxygen (O ₂ ) atmosphere at 1100 ° C. to 1150 ° C. for about 60 minutes, thereby forming a silicon oxide film 2 having a thickness of 1500 ° to 20,000 °.
a and 2b are formed.

Next, a part of the silicon oxide film 2a formed on one main surface 1a of the silicon substrate 1 is removed by photolithography. Thereby, one main surface 1
a using the silicon oxide film 2a formed on
The epitaxial layer 3 is formed by growing a semiconductor crystal on the silicon substrate portion selected by the mask 2a.
As a method of growing a semiconductor crystal, for example, metal organic vapor phase epitaxy or molecular beam epitaxy is used.

FIG. 2 shows one main surface 1 a of the silicon substrate 1.
2 shows a plan view shape of an insulating mask formed by removing a part of the silicon oxide film 2a formed in FIG. In the silicon oxide film 2a, a portion covering the formation position of the LED array is removed in a strip shape, and a portion along the longitudinal direction (the left-right direction in FIG. 2) of the strip-shaped removed portion 7 has an interval between the longitudinal directions. In the shape of a rectangle. A semiconductor crystal is grown in the strip-shaped removal part 7 and in the rectangular removal part 8, and the LED is placed in the strip-shaped removal part 7.
An epitaxial layer 3 for forming an array is grown, and an epitaxial layer 3 ′ having a similar structure is grown in the rectangular removal portion 8.

Note that a portion of one main surface 1a of the silicon substrate 1 along the longitudinal direction of the strip-shaped removed portion 7 is
Since the lead portion a is arranged, it is not necessary to grow a semiconductor crystal, and the semiconductor crystal can be covered with a silicon oxide film. However, when a semiconductor crystal is grown on the strip-shaped removed portion 7 of the insulating mask, if the semiconductor crystal is not grown on a portion along the longitudinal direction of the strip-shaped removed portion 7, the area of the portion where the semiconductor crystal grows on the silicon substrate 1 is required. Becomes too small, and a semiconductor crystal grows on the insulating mask. The semiconductor crystal grown on the insulating mask composed of such a silicon oxide film 2a has poor crystallinity, and deteriorates the crystallinity of the epitaxial layer grown in the strip-shaped removed portion 7.

Then, the portion along the longitudinal direction of the strip-shaped removed portion 7 of the insulating mask is removed at intervals in the longitudinal direction,
A semiconductor crystal is epitaxially grown also in the removed portion to prevent the crystallinity of the epitaxial layer from deteriorating, thereby improving the light emission characteristics of the LED 5. At this time, if the portion along the longitudinal direction of the strip-shaped removed portion 7 of the insulating mask is removed without an interval between the longitudinal directions, the difference in the thermal expansion coefficient between the semiconductor crystal grown in that portion and the silicon substrate 1 causes the substrate 1 Since the warp becomes large, the portion along the longitudinal direction of the strip-shaped removed portion 7 of the insulating mask is removed at intervals in the longitudinal direction.

When a mask is formed by removing a part of the silicon oxide film 2a, one main surface 1 of the silicon substrate 1 is removed.
It is preferable to remove the semiconductor light emitting device 4 by digging it deeper by about 1 μm to 2 μm than “a” because the thickness of the semiconductor light emitting device 4 can be reduced.

Next, as shown in FIG. 3, the epitaxial layer 3 grown in the strip-shaped removed portion 7 is separated into a plurality of portions at intervals in the longitudinal direction to form an LED array. This separation is performed by, for example, photo etching. At this time, the epitaxial layer 3 'formed in the rectangular removal portion 8 is also removed. Although the epitaxial layer 3 'grown in the rectangular removal portion 8 may be left without being removed, the removal of the epitaxial layer 3' eliminates bending of the lead-out portion of the electrode 6a, and can prevent cracks from occurring in the electrode 6a.

Next, the passivation film 9 is formed,
Thereafter, an electrode 6a is formed as shown in FIG. Finally, an electrode 6b on the other main surface 1b side of the substrate 1 is formed.

According to the above configuration, by using the silicon oxide film 2a formed on the one main surface 1a of the silicon substrate 1 as an insulating mask, only a necessary portion of the one main surface 1a of the silicon substrate 1 is selected. The semiconductor crystal is epitaxially grown. Thereby, the warpage of the substrate 1 due to a temperature change is reduced, and cracks are prevented from being formed in the epitaxial layer 3 as compared with the case where a semiconductor crystal is grown on one entire main surface of the silicon substrate. At this time, since the single epitaxial layer 7 grown in the strip-shaped removed portion 7 of the insulating mask is separated into a plurality of portions at intervals in the longitudinal direction, an LED array is formed. The stress state in the epitaxial layer becomes uniform as compared with the case where a large number of epitaxial layers constituting the above are grown, so that the crystallinity in the epitaxial layer can be prevented from deteriorating, and the light emission characteristics of the LED can be improved.

Further, since the stable silicon oxide films 2a and 2b are formed on both the one main surface 1a and the other main surface 1b of the silicon substrate 1 by the thermal oxidation method, the silicon substrate 1 and the silicon oxide film 2a are formed. 2b are not easily decomposed, and the incorporation of silicon into the inside of the epitaxial layer 3 is reduced, and the crystallinity of the epitaxial layer 3 can be improved. Thereby, the light emission characteristics of the LED 5 can be improved.

FIG. 7 shows a step of forming the epitaxial layer 3 according to the first invention of the present invention.

First, the natural oxide film on the silicon substrate selected by the insulating mask is removed at a high temperature of about 950.degree.

Next, once the temperature is lowered, 660
The temperature is raised to about ° C. to epitaxially grow the semiconductor crystal 3A that mainly forms the buffer layer 3a. The semiconductor crystal 3
A is, for example, gallium arsenide, gallium arsenide phosphorus (GaAs)
sP), gallium phosphide (GaP) or the like can be used. Thermal stress is applied by repeating a plurality of cycles of once lowering the temperature of the growth layer of the semiconductor crystal 3A and then increasing the temperature to about 850 ° C. Thereby, the dislocation is confined in the buffer layer 3a or escapes to the side of the buffer layer 3a, and the dislocation in the semiconductor layers 3b, 3c, and 3d constituting the LED 5 is reduced.

The first strained superlattice layer 14 is formed on the growth layer of the semiconductor crystal 3A. Thereby, the dislocation is confined in the buffer layer 3a or escapes to the side of the buffer layer 3a, and the dislocation in the semiconductor layers 3b, 3c, and 3d constituting the LED is reduced.

A semiconductor crystal 3A mainly constituting the buffer layer 3a is epitaxially grown on the first strained superlattice layer 14, and a second strained superlattice layer 15 is formed on the growth layer of the semiconductor crystal 3A. As a result, dislocations that have passed through the first strained superlattice layer 14 are confined in the buffer layer 3a or released to the side of the buffer layer 3a, thereby reducing dislocations in the semiconductor layers 3b, 3c, and 3d constituting the LED.

Next, a semiconductor crystal constituting an LED is epitaxially grown on the buffer layer 3a. As the semiconductor crystal, for example, aluminum gallium arsenide, gallium arsenide, indium gallium arsenide, and gallium arsenide phosphorus can be used.

Each of the strained superlattice layers 14 and 15 is composed of first semiconductor crystals 14a and 15a having a different lattice constant from semiconductor crystal 3A that mainly forms buffer layer 3a, and a first semiconductor crystal 14a and 15a The second semiconductor crystals 14b and 15b having different constants are alternately and repeatedly grown a plurality of times. In this embodiment, the semiconductor crystal 3A that mainly constitutes the buffer layer 3a is gallium arsenide, the first semiconductor crystals 14a, 15a of the strained superlattice layers 14, 15 are indium gallium arsenide, and the second semiconductor crystals 14b, 1b
5b is gallium arsenide. As a result, in each of the strained superlattice layers 14, 15, the first semiconductor crystals 14a, 1
Stress acts between the growth layer 5a and the growth layers of the second semiconductor crystals 14b and 15b, and the stress causes strain in the strained superlattice layers 14 and 15 in a direction perpendicular to the growth direction.
It is assumed that the magnitude of this strain varies along the growth direction,
The distribution is as shown by the arrow in the figure. That is, the strain in each of the strained superlattice layers 14 and 15 gradually decreases upward in the growth direction (upward in the drawing), and the strain is maximized at the lower end in the growth direction.

Thus, by reducing the strain at the upper end in the growth direction of each of the strained superlattice layers 14, 15, the occurrence of dislocations from the upper end in the growth direction is reduced, and lower than the upper end in the growth direction. By maximizing the strain, the dislocation is effectively confined inside the buffer layer 3a or escaped to the side.

The magnitude of the strain in the strained superlattice layers 14 and 15 can be changed by changing the composition and the thickness of the semiconductor crystal constituting the strained superlattice layer. For example, when the first semiconductor crystals 14a, 15a of the strained superlattice layers 14, 15 are indium gallium arsenide crystals and the second semiconductor crystals 14b, 15b are gallium arsenide crystals, the first semiconductor crystals 14a, 15a InAs
If the composition ratio of GaAs to GaAs gradually decreases in the upward direction of crystal growth, the strain in strained superlattice layers 14 and 15 gradually decreases in the upward direction of growth.
Further, if the thickness of the first semiconductor crystals 14a, 15a is gradually reduced in the upward direction in the crystal growth direction, the strain in the strained superlattice layers 14, 15 is gradually reduced in the upward direction in the growth direction.

With the above configuration, E.I. P. D. To 3 × 10
⁵ / cm ² could be reduced.

The type of the semiconductor crystal forming the strained superlattice layers 14 and 15 may be appropriately selected according to the semiconductor crystal mainly forming the buffer layer 3a. For example, the first semiconductor crystals 14a and 15a may be made of In. and _x Ga _1-x as, the second semiconductor crystal 14b, 15b and so such an in _y Ga _1-y as, may be configured with different indium gallium arsenide composition ratios.

In the above embodiment, the buffer layer 3a has
Although the strained superlattice layers 15 and 16 are formed, one layer may be formed, or three or more layers may be formed.

In the above embodiment, each strained superlattice layer 1
The strains at 4 and 15 were gradually decreased upward in the growth direction, and the strain was greatest at the lower end in the growth direction. However, as shown in FIG. The strain may be the largest in the middle of the growth direction.
The portion where the strain is the largest may be arranged below the upper end in the crystal growth direction.

FIG. 9 shows a step of forming the epitaxial layer 3 according to the second invention.

First, the natural oxide film on the silicon substrate selected by the insulating mask is removed at a high temperature of about 950 ° C.

Next, once the temperature is lowered,
The temperature is raised to about ° C. to epitaxially grow the semiconductor crystal 3A that mainly forms the buffer layer 3a. The semiconductor crystal 3
As A, for example, gallium arsenide, gallium arsenide phosphorus,
Gallium phosphorus or the like can be used. A thermal stress is applied by repeating a cycle in which the temperature of the growth layer of the semiconductor crystal layer 3A is once lowered and then raised to about 850 ° C. a plurality of times. Thereby, the dislocation is confined in the buffer layer 3a or escapes to the side of the buffer layer 3a, and the dislocation in the semiconductor layers 3b, 3c, and 3d constituting the LED 5 is reduced.

On the growth layer of the semiconductor crystal 3A, the first
A strained superlattice layer 14 is formed. As a result, dislocations are confined in the buffer layer 3a or released to the side, and dislocations in the semiconductor layers 3b, 3c, and 3d constituting the LED are reduced.

A semiconductor crystal 3A mainly constituting the buffer layer 3a is epitaxially grown on the first strained superlattice layer 14, and a second strained superlattice layer 15 is formed on the growth layer of the semiconductor crystal 3A. As a result, dislocations that have passed through the first strained superlattice layer 14 are confined in the buffer layer 3a or released to the side of the buffer layer 3a, thereby reducing dislocations in the semiconductor layers 3b, 3c, and 3d constituting the LED.

A semiconductor crystal mainly constituting the buffer layer 3a is epitaxially grown on the second strained superlattice layer 15, and a third strained superlattice layer 16 is formed on the growth layer of the semiconductor crystal 3A. As a result, dislocations passing through the second strained superlattice layer 15 are confined in the buffer layer 3a or released to the side, and the semiconductor layers 3b, 3c, 3
Reduce dislocations in d.

Next, a semiconductor crystal constituting an LED is epitaxially grown on the buffer layer 3a. As the semiconductor crystal, for example, aluminum gallium arsenide, gallium arsenide, indium gallium arsenide, and gallium arsenide phosphorus can be used.

Each of the strained superlattice layers 14, 15, and 16 includes first semiconductor crystals 14a, 15a, and 16a having a different lattice constant from semiconductor crystal 3A that mainly forms buffer layer 3a, and first semiconductor crystal 14a. , 15a, 16a and second semiconductor crystals 14b, 15b, 16b having different lattice constants are alternately and repeatedly grown a plurality of times. In the present embodiment, the semiconductor 3A that mainly constitutes the buffer layer 3a is gallium arsenide, and the first of the strained superlattice layers 14, 15, 16
Semiconductor crystals 14a, 15a, 16a are indium gallium arsenide, and the second semiconductor crystals 14b, 15b, 16
b is gallium arsenide. As a result, the first semiconductor crystal 14 is formed in each of the strained superlattice layers 14, 15, and 16.
a, 15a, 16a and second semiconductor crystal 14
Stress acts between the growth layers b, 15b, and 16b, and the stress causes strain in the strained superlattice layers 14, 15, 16 in a direction perpendicular to the growth direction. Each strained superlattice layer 14,
The magnitudes of the distortions 15 and 16 are different from each other as indicated by arrows in the figure. That is, the strain in the strained superlattice layer 16 at the uppermost part in the crystal growth direction is minimized, and the strain in the strained superlattice layer 14 at the lowermost part in the crystal growth direction is maximized.

As a result, the strain at the upper end in the growth direction of the strained superlattice layer 16 in the uppermost direction in the crystal growth direction is reduced, so that the occurrence of dislocations from the upper end in the growth direction is reduced, and By maximizing the strain of the strained superlattice layer 14 below the uppermost strained superlattice layer 16, dislocations are effectively confined inside the buffer layer 3a or escaped to the side.

The magnitude of the strain in the strained superlattice layers 14, 15, 16 can be changed by changing the composition and the thickness of the semiconductor crystal layer constituting the strained superlattice layer. For example, the first semiconductor crystals 14a, 15a, 16a of the strained superlattice layers 14, 15, 16 are made of indium gallium arsenide crystal, and the second semiconductor crystals 14b, 15b, 16
When b is a gallium arsenide crystal, the first semiconductor crystal 1
If the composition ratio of InAs to GaAs in 4a, 15a, and 16a is maximized in the strained superlattice layer 14 at the bottom in the crystal growth direction and is minimized in the strained superlattice layer 16 at the top in the crystal growth direction, The strain of the upper strained superlattice layer 16 is minimized, and the strain of the strained superlattice layer 14 located at the bottom in the crystal growth direction is maximized. Also, the strained superlattice layer 14,
First semiconductor crystals 14a, 15 constituting 15, 16
If the film thicknesses of a and 16a are maximized in the strained superlattice layer 14 at the bottom of the crystal growth direction and minimized in the strained superlattice layer 16 at the top of the crystal growth direction, the strained superlattice layer at the top of the crystal growth direction is obtained. 16 is minimized, and the strain of the strained superlattice layer 14 at the bottom in the crystal growth direction is maximized.

With the above configuration, E.I. P. D. To 3 × 10
⁵ / cm ² could be reduced.

The semiconductor crystals constituting the strained superlattice layers 14, 15, 16 may be appropriately selected according to the semiconductor crystals constituting the buffer layer 3a. For example, the first semiconductor crystals 14a, 15a, 16a Is In _x Ga _{1 -x} As, and the second semiconductor crystals 14b, 15b, 16b are In _y
It is also possible to use indium gallium arsenide having a different composition ratio, such as Ga _1-y As.

In the above embodiment, the buffer layer 3a has
Although the strained superlattice layers 14, 15, and 16 are formed, two layers or four or more layers may be formed.

In the above embodiment, each strained superlattice layer 1
As for the strains at 4, 15, and 16, the strain of the strained superlattice layer 16 at the uppermost part in the crystal growth direction was minimized, and the strain of the strained superlattice layer 14 at the lowermost part in the crystal growth direction was maximized, as shown in FIG. As described above, the strained superlattice layers 15 at the center in the growth direction and the strained superlattice layers 15
May have the largest distortion. In short,
A plurality of strained superlattice layers having different strain magnitudes are formed at intervals in the crystal growth direction in the buffer layer 3a, and the strained superlattice layer having the largest strain is arranged to be larger than the strained superlattice layer located at the top in the crystal growth direction. What is necessary is just to arrange | position below.

[0061]

According to each method of the present invention, a semiconductor crystal is epitaxially grown by using a silicon oxide film formed on one main surface of a silicon substrate as an insulating mask to constitute an LED array. Can be prevented from being caused in the epitaxial layer due to the difference in the coefficient of thermal expansion.

According to the first aspect of the present invention, the magnitude of the strain in the strained superlattice layer formed in the buffer layer is made different along the growth direction, and the portion where the strain is greatest is located at a position higher than the upper end in the crystal growth direction. By arranging it below, it is possible to reduce crystal defects of the LED and improve the light emission characteristics.

According to the second aspect of the present invention, a plurality of strained superlattice layers having different strain magnitudes are formed in the buffer layer at intervals in the crystal growth direction, and the strained superlattice layer having the largest strain is formed by crystal growth. By arranging it below the uppermost strained superlattice layer in the direction, crystal defects of the LED can be reduced and light emission characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a manufacturing process of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a plan configuration diagram of an insulating mask according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a manufacturing process of the semiconductor light emitting device according to the embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 6 is a diagram showing a cross-sectional configuration of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 7 is a configuration explanatory view of the semiconductor light emitting device according to the embodiment of the first invention.

FIG. 8 is a configuration explanatory view of a semiconductor light emitting device according to a different embodiment of the first invention.

FIG. 9 is a configuration explanatory view of a semiconductor light emitting device according to an example of the second invention.

FIG. 10 is a configuration explanatory view of a semiconductor light emitting device according to a different embodiment of the second invention.

FIG. 11 is a diagram showing a relationship between time and temperature in a semiconductor manufacturing process.

FIG. 12 is a diagram illustrating a configuration of a conventional semiconductor light emitting device.

FIG. 13 is a configuration explanatory view of a conventional semiconductor light emitting device.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2a silicon oxide film 2b silicon oxide film 3 epitaxial layer 3a buffer layer 5 LED 14, 15, 16 strained super lattice layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 33/00 H01S 3/18

Claims (2)

(57) [Claims] A silicon oxide film formed on one main surface of a silicon substrate is partially removed, thereby using the silicon oxide film as an insulating mask, and forming a buffer layer on the silicon substrate portion selected by the insulating mask. The main constituent semiconductor crystal is epitaxially grown, a strained superlattice layer is formed in the buffer layer, and the magnitude of the strain in the strained superlattice layer is varied along the growth direction. Is disposed below the upper end in the crystal growth direction, and a semiconductor crystal constituting an LED is epitaxially grown on the buffer layer thereof. 2. A method according to claim 1, wherein a part of the silicon oxide film formed on one main surface of the silicon substrate is removed, and the silicon oxide film formed on the one main surface is used as an insulating mask. The semiconductor crystal that mainly constitutes the buffer layer is epitaxially grown on the silicon substrate part, and a plurality of strained superlattice layers having different strain magnitudes are formed in the buffer layer at intervals in the crystal growth direction to minimize the strain. A large strained superlattice layer is arranged below the uppermost strained superlattice layer in the crystal growth direction, and an LED is placed on the buffer layer.
A method for manufacturing a semiconductor light emitting device, comprising epitaxially growing a semiconductor crystal constituting the semiconductor light emitting device.